The dreaded specter of drought is being feared already in some areas of the Southeast, with much of the region reporting abnormally dry conditions in early spring.
The Southeast usually receives most of its rainfall during the fall and winter months, when its lakes, rivers and groundwater supplies are recharged. But that didn’t occur this year, and dry conditions have continued into the spring.
The U.S. Drought Monitor, an online report prepared by several federal agencies, shows normal moisture levels for most of Tennessee, Kentucky, Mississippi and Alabama. However, it classifies Florida, South Carolina, most of Georgia and smaller portions of Alabama, Mississippi and Louisiana as unusually dry. A section of central North Carolina already is classified as being in a severe drought, while Virginia and most of North Carolina are in a moderate drought. Virginia had the driest March since record-keeping began in 1895, and some shallow wells were reportedly running dry in eastern North Carolina. Virginia officials said that at this point, it’ll probably be difficult to avoid a drought “of some magnitude.”
In Georgia, the past six months have been abnormally dry, says David Emory Stooksbury, state climatologist. “Rainfall during the cool season, October through March, is needed to recharge soil moisture, groundwater and reservoirs. But because of the dry cool season, the soil moisture hasn't been adequately recharged. As a result, the state had abnormally dry soils and low stream flows for April,” he says.
Soil moisture was reported the lowest in the Chattahoochee and Savannah River Valleys and along the fall line. Only extreme southeast Georgia had near normal soil moisture for April, says Stooksbury.
U.S. Geological Survey stream gauges were showing low flows across the entire state in April, he adds. “Many streams are between the 10th and 25th percentile for the date. This means that at the 10th percentile, we expect the stream flow to be greater than the current value 90 years out of 100 for this date. At the 25th percentile, we expect the stream flow to be greater 75 years out of 100,” he says.
Based on USGS data, groundwater levels were showing good recharge in November and December 2005. However, with abnormal dryness during February through mid-April, these levels were beginning to drop, says Stooksbury.
The normal recharge season for groundwater is over. So groundwater levels are expected to keep dropping through summer into fall. The state’s major reservoirs are in good shape. Levels will begin to drop, though, without adequate rainfall soon,” he said in late April.
Alabama Agriculture & Industries Commissioner Ron Sparks has announced that a statewide drought monitoring system will be established throughout Alabama for the first time this year.
“Drought is a devastating climatic condition that affects every aspect of life,” says Sparks. “Alabama experiences a severe or extreme drought approximately every 13 years with the duration of each drought event lasting from one to seven years. Drought and its effects can be catastrophic for farmers, industries, water supply and wildlife. The ability to accurately determine the magnitude and to predict the onset or duration of a drought event is extremely important. This can be accomplished through drought monitoring.”
A network of five observation wells which transmit ground water level data on a real-time basis through satellite telemetry will begin operating July 1, 2006, says Sparks. Four wells will be located in Baldwin, Dekalb, Franklin and Lawrence, and Covington and Coffee counties. The fifth well will be located in a county in central Alabama.
“The locations were chosen because they are constructed in aquifer recharge areas and are in areas of extensive agricultural land use. The ultimate goal of this project is to establish a network of 25 wells over a five-year period which will provide information that allows observation of the onset and duration of drought conditions in ground water,” he says.
The drought monitoring system will provide valuable information that can be used to determine when a drought may occur and for how long, says Sparks. “It could be a tremendous help to anyone in the agricultural industry who relies on water to grow or produce their products. As we increase the number of wells, we improve our chances of helping to prepare for drought and maybe even prevent it in the future.”
Approximately 40 percent of Alabama’s water supplies are withdrawn from the state’s groundwater resources, providing approximately 100 percent of the water used for rural domestic supplies and 34 percent of the water used for public supplies. In addition, more than 33 percent of the water used for agricultural purposes is withdrawn from wells. Much of the flow in streams and the water in lakes and wetlands are sustained by the discharge of groundwater, particularly during periods of dry weather.
A comprehensive drought monitoring program, says Sparks, utilizes temperature, evaporation, precipitation, soil moisture, surface water levels and shallow groundwater levels to accurately monitor drought conditions.
Natural discharge from shallow aquifers provides base flow to streams and sustains the water in lakes and wetlands particularly during periods of dry weather, he says. “Therefore, declining shallow groundwater levels are important indicators of drought conditions and indications of the duration and severity of drought,” says Sparks.
The water-level data from these wells will be automatically collected and transmitted by satellite telemetry every four hours to the USGS and displayed on the USGS Alabama Water Science Center Web site at http://al.water.usgs.gov. This data also will be a part of the USGS Ground Water Climate Response Network at http://watermonitor.gov/water_gw.shtml.
“The purpose and objectives of this project will be to establish a network of continuous-recording water-level monitoring wells in selected areas in Alabama to monitor the effects of drought and other climate variability on groundwater levels as part of a comprehensive drought monitoring effort. In addition, the system can monitor short-term variability and long-term trends in water levels to determine the effects of climatic variability on groundwater recharge and storage.”